Angiogenesis, the formation of new blood vessels from preexisting vasculature, is a major component in several retinal vascular diseases causing blindness, such as retinopathy of prematurity, proliferative diabetic retinopathy, diabetic macular edema, and age-related macular degeneration. Ocular neovascularization is the abnormal or excessive formation of blood vessels in the eye. Ocular neovascularization has been shown to be relevant in both diabetic retinopathy and age-related macular degeneration.
Age-related macular degeneration (AMD) is a leading cause of blindness in the elderly population and is recognized as dry and wet AMD forms. The dry, or nonexudative, form involves both atrophic and hypertrophic changes of the retinal pigment epithelium (RPE). The dry form is characterized by macular drusen which are pigmented areas containing dead cells and metabolic products that distort the retina and eventually cause loss of acute vision. Patients with nonexudative AMD (dry form) can progress to the wet, or exudative or neovascular, AMD, in which pathologic choroidal neovascular membranes (CNVM) develop under the retina, leak fluid and blood, and, ultimately, cause a centrally blinding disciform scar over a relatively short time frame if left untreated. Choroidal neovascularization (CNV), the growth of new blood vessels from the choroid capillary network across the Bruch's membrane/RPE interface into the neural retina, results in retinal detachment, subretinal and intraretinal edema, and scarring.
Diabetes can affect the eye in a number of ways. Diabetic retinopathy (DR) is a complication of diabetes that results from damage to the blood vessels of the light-sensitive tissue at the back of the eye (the retina). At first, diabetic retinopathy may cause no symptoms or only mild vision problems. Eventually, however, diabetic retinopathy can result in blindness. Diabetic macular edema (DME) is the swelling of the retina in diabetes mellitus due to leaking of fluid from blood vessels within the macula.